Depends where you live

In the UK its technically illegal to rip a CD to your own PC to back it up, for example, see the recent high court case(s) about it where the government won against Brennan (who make hifi gear which can do this) - no different to this app.

In 2014 the government passed a law making ripping explicitly legal. In 2015 the music industry sued and the High Court ruled that the law was contrary to some EU directive and thus invalid. But I don't know if that law was annulled by the court decision, or if it was merely dormant until we left the EU. The Brennan ripping devices are still on sale. Do you have a link to this case?

I was under the impression that this had been changed in the last few years. Do you have a link for that case?

I’m still getting adverts for Brennan thingies online, did they find a way around the court judgement?

To be fair, the music industry knows they couldn't beat Google in court on this.

The same can't be said for OP who probably doesn't have the time or money to fight it as evidenced by this post.

Google Music (fka Google Play Music) have license agreements! e.g. https://www.cmrra.ca/socan-csi-strike-licensing-deal-with-go...

Part of the reason google/youtube are quasi-monopolistic is that they've already been through all of this, they've had the arguments and the lawsuits in various different territories, and they've reached agreements and paid money to deal with the copyright issues.

They had matching though, so if you had a lousy quality mp3 that matches through audio fingerprinting it would be upgraded.